Novel racemosin B derivatives as new therapeutic agents for aggressive breast cancer

Carbazole derivatives show anti-cancer activity and are of great interest for drug development. In this study, we synthesized and analyzed several new alkylamide derivatives of racemocin B, a natural indolo[3,2-a]carbazole molecule originally isolated from the green alga Caulerpa racemose. Several alkylamide derivatives were found to exhibit moderate to strong growth inhibition against human breast cancer cell lines. They induced G2/M cell cycle arrest and apoptosis in the aggressive triple-negative breast cancer cell line MDA-MB-231. Among these derivatives, compound 25 with the lowest IC₅₀ induced cell death by suppressing autophagy. This was accompanied by inhibition of autophagic flux and accumulation of autophagy protein 1 light chain 3, LC3II, and p62. The novel alkylamide derivative offers a potential new treatment for human breast cancer.     

Localization of DNA probes for human ribosomal genes on barley chromosomes]

To estimate the possibility of plant genome mapping using human genome probes, the probes fluorescent in situ hybridization (FISH) of human 18S-28S rDNA (clon 22F9 from the LA-13NCO1 library) was carried out on chromosomes of the spring barley Hordeum vulgare L. As a control, wheat rDNA probe (clon pTa71) was taken. Hybridization of the wheat DNA probe revealed two major labelling sites on mitotic barley chromosomes 5I (7H) and 6I (6H), as well as several minor sites. With the human DNA probe, signals were detected in the major sites of the ribosomal genes on chromosomes 5I (7H) and 6I (6H) only when the chromosome preparations were obtained using an optimized technique with obligatory pepsin treatment followed by hybridization. Thus, this study demonstrates that physical mapping of plant chromosomes with human DNA probes that are 60 to 75% homologous to the plant genes is possible. It suggests principal opportunity for the FISH mapping of plant genomes using probes from human genome libraries, obtained in the course of the total sequencing of the human genomes and corresponding to the coding regions of genes with known functions.     

Genetic and epigenetic changes of rDNA in a synthetic allotetraploid, Aegilops sharonensis x Ae. umbellulata.

The synthetic allotetraploid Aegilops sharonensis x Ae. umbellulata (genomic formula S(sh)U) was used to study inheritance and expression of 45S rDNA during early stages of allopolyploid formation. Using silver staining, we revealed suppression of the NORs (nucleolar organizing regions) from the S(sh) genome in response to polyploidization. Most allopolyploid plants of the S(2)-S(4) generations retained the chromosomal location of 45S rDNA typical for the parental species, except for two S(3) plants in which a deletion of the rDNA locus on one of the homologous 6S(sh) chromosomes was revealed. In addition, we found a decrease in NOR signal intensity on both 6S(sh) chromosomes in a portion of the S(3) and S(4) allopolyploid plants. As Southern hybridization showed, the allopolyploid plants demonstrated additive inheritance of parental rDNA units together with contraction of copy number of some rDNA families inherited from Ae. sharonensis. Also, we identified a new variant of amplified rDNA unit with MspAI1 restriction sites characteristic of Ae. umbellulata. These genetic alterations in the allopolyploid were associated with comparative hypomethylation of the promoter region within the Ae. umbellulata-derived rDNA units. The fast uniparental elimination of rDNA observed in the synthetic allopolyploid agrees well with patterns observed previously in natural wheat allotetraploids.     

Production of alloplasmic and euplasmic wheat-barley ditelosomic substitution lines 7H<Superscript>1</Superscript>L<Superscript>mar</Superscript>(7D) and analysis of the 18S/5S mitochondrial repeat in these lines

Alloplasmic lines of common wheat with disomic substitution of chromosome 7D for telocentric chromosome 7H¹L^mar of barley H. marinum subsp. gussoneanum Hudson were isolated from the plants of generation BC₃, produced as a result of backcrossing of barley-wheat hybrids H. marinum subsp. gussoneanum (2n = 28) × T. aestivum (2n = 42), Pyrotrix, cultivar, with 28 common wheat cultivars Pyrotrix 28 and Novosibirskaya 67. Chromosome substitution pattern was determined using SSR analysis and C-banding. In preliminary genomic in situ hybridization experiments, telocentric chromosomes were assigned to wild barley was established. In the BC₃F₈ generations of three alloplasmic lines with the 7H¹L^mar(7D) substitution type the differences in fertility manifestation were observed: most of the L-32(1) plants were sterile, in line L-32(2) only sporadic plants were sterile, and line L-32(3) was fertile. Simultaneously with these experiments, using selfpollinated progeny of the hybrids obtained in crosses of common wheat cultivar Saratovskaya 29 (2n = 41), monosomic for chromosome 7D, with common wheat cultivar Pyrotrix 28 with addition of pair of telocentric chromosomes 7H¹L^mar (7D) of barley H. marinum subsp. gussoneanum, euplasmic wheat-barley ditelosomic substitution 7H¹L^mar (7D) lines were isolated. The lines obtained had normal fertility. PCR analysis of the 18S/5S mitochondrial repeat (hereafter, mtDNA sequence) in alloplasmic and euplasmic ditelosomic substitution lines 7H¹L^mar(7D) was performed. In the plants from alloplasmic sterile line L-32(1), the sequences only of the barley (maternal) type were revealed, while the plants from alloplasmic fertile lines L-32(2) and L-32(3) demonstrated heteroplasmy (the presence of barley- and wheat-like sequences within one individual). In euplasmic ditelosomic substitution lines the presence of only wheat-like 18S/5S mitochondrial repeat sequences was observed. The results indicate that the presence of barley-like mtDNA sequences in alloplasmic substitution lines was not associated with the presence of barley chromosomes in their nuclear genomes.     

Diversity and the origin of the European population of <Emphasis Type="Italic">Triticum dicoccum</Emphasis> (Schrank) Schuebl. As revealed by chromosome analysis

Cluster analysis of the Triticum dicoccum chromosome passports by artificial neural networks and UPGMA divided the European T. dicoccum population into two groups, West European and Volga-Balkan. The West European T. dicoccum accessions displayed a predominance of the marker translocation T7A:5B (67% of the accessions), which was also found in a few accessions from other countries (Turkey, Iran, and northern Africa), and were similar in chromosome C-banding patterns. The Volga-Balkan T. dicoccum accessions differed in the C-banding patterns of some chromosomes from the West European accessions, thus probably originating from another founder population. It was assumed that the T. dicoccum accessions carrying the T7A:5B translocation had a common origin and that the wild T. dicoccum population of the Middle East (Syria and Lebanon) contributed to the origin of West European T. dicoccum.     

Robust dynamics of Amazon dieback to climate change with perturbed ecosystem model parameters

Climate change science is increasingly concerned with methods for managing and integrating sources of uncertainty from emission storylines, climate model projections, and ecosystem model parameterizations. In tropical ecosystems, regional climate projections and modeled ecosystem responses vary greatly, leading to a significant source of uncertainty in global biogeochemical accounting and possible future climate feedbacks. Here, we combine an ensemble of IPCC‐AR4 climate change projections for the Amazon Basin (eight general circulation models) with alternative ecosystem parameter sets for the dynamic global vegetation model, LPJmL. We evaluate LPJmL simulations of carbon stocks and fluxes against flux tower and aboveground biomass datasets for individual sites and the entire basin. Variability in LPJmL model sensitivity to future climate change is primarily related to light and water limitations through biochemical and water‐balance‐related parameters. Temperature‐dependent parameters related to plant respiration and photosynthesis appear to be less important than vegetation dynamics (and their parameters) for determining the magnitude of ecosystem response to climate change. Variance partitioning approaches reveal that relationships between uncertainty from ecosystem dynamics and climate projections are dependent on geographic location and the targeted ecosystem process. Parameter uncertainty from the LPJmL model does not affect the trajectory of ecosystem response for a given climate change scenario and the primary source of uncertainty for Amazon ‘dieback’ results from the uncertainty among climate projections. Our approach for describing uncertainty is applicable for informing and prioritizing policy options related to mitigation and adaptation where long‐term investments are required.     

Comparative cytogenetic analysis of hexaploid Avena L. species

Using C-banding method and in situ hybridization with the 45S and 5S rRNA gene probes, six hexaploid species of the genus Avena L. with the ACD genome constitution were studied to reveal evolutionary karyotypic changes. Similarity in the C-banding patterns of chromosomal and in the patterns of distribution of the rRNA gene families suggests a common origin of all hexaploid species. Avena fatua is characterized by the broadest intraspecific variation of the karyotype; this species displays chromosomal variants typical of other hexaploid species of Avena. For instance, a translocation with the involvement of chromosome 5C marking A. occidentalis was discovered in many A. fatua accessions, whereas in other representatives of this species this chromosome is highly similar to the chromosome of A. sterilis. Only A. fatua and A. sativa show slight changes in the morphology and in the C-banding pattern of chromosome 2C. These results can be explained either by a hybrid origin of A. fatua or by the fact that this species is an intermediate evolutionary form of hexaploid oats. The 7C-17 translocation was identified in all studied accessions of wild and weedy species (A. sterilis, A. fatua, A. ludoviciana, and A. occidentalis) and in most A. sativa cultivars, but it was absent in A. byzantina and in two accessions of A. sativa. The origin and evolution of the Avena hexaploid species are discussed in context of the results.     

Proterozoic phytoplankton and timing of Chlorophyte algae origins

Abstract: Morphological and reproductive features and cell wall ultrastructure and biochemistry of Proterozoic acritarchs are used to determine their affinity to modern algae. The first appearance datum of these microbiota is traced to infer a minimum age of the divergence of the algal classes to which they may belong. The chronological appearance of microfossils that represent phycoma‐like and zygotic cysts and vegetative cells and/or aplanospores, respectively, interpreted as prasinophyceaen and chlorophyceaen microalgae is related to the Viridiplantae phylogeny. An inferred minimum age of the Chlorophyte origin is before c. 1800 Ma, the Prasinophyceae at c. 1650 Ma and the Chlorophyceae at c. 1450 Ma. These divergence times differ from molecular clock estimates, and the palaeontological evidence suggests that they are older.     

Evolution of <Emphasis Type="Italic">Triticum aethiopicum</Emphasis> Jakubz. from the Position of Chromosome Analysis

Cytogenetic analysis was conducted on a set of 67 Ethiopian wheat accessions collected by the expedition of N.I. Vavilov in 1927 and 85 years later by the Joint Ethiopian–Russian Biological Expedition (JERBE) in 2012 in the same sites of Ethiopia. The preservation of the polymorphism system of heterochromatic chromosome sites upon the change in the Ethiopian wheat population structure over the past period owing to a frequency shift of some specific chromosome variants and an increase in the proportion of genotypes carrying marker rearrangements was demonstrated. The unevenness of the geographical distribution of the 2A:4B translocation and of the 5A inversion was identified, and it was demonstrated that wheat accessions from Eritrea were cytogenetically the most isolated from the population from the central regions of Ethiopia. A low level of the Ethiopian wheat polymorphism was found along with the prevalence of the same chromosome rearrangement variants, which was indicative of monophyletic origin of the species. It was suggested that Triticum aethiopicum could have diverged from Ethiopian emmer as a result of hybridization with other wheat species, while subsequent evolution of these species occurred independently. Evidence for the participation of Ethiopian wheat in the formation of the gene pool of the unique Moroccan group of T. dicoccum was obtained.